In mobile communication systems, a channel card is configured to use different system clocks depending on the Bandwidth (BW). For instance, 500 MHz system clock is used for 8.75 MHz BW, 56 MHz system clock for 10 MHz BW, and 44.8 MHz system clock for 5 MHz BW. In a picocell channel card of WiBro system, 44.8 MHz system clock is used.
Meanwhile, a radio communication apparatus includes an RF block and a digital block. Typically, the RF block uses a system clock which minimizes the phase noise, and the digital block is designed to acquire stable Pulse per 2 Seconds (PP2S) signal, which is a reference signal for data processing. The 44.8 MHz system clock, used in the WiBro picocell, is locked based on the GPS clock (10 MHz in general) received from GPS satellites. In this case, however, the frequency of the 10 Mhz GPS clock is not an integer multiple of the 44.8 Mhz used in the WiBro picocell channel card, whereby the phase of 10 Mhz GPS signal is not accurately synchronized to that of the 44.8 Mhz.
In order to overcome this problem, an additional logic is used for converting the 10 MHz frequency of GPS signal to an integer multiple of the system reference clock of 44.8 MHz used in the WiBro picocell channel card. However, this conventional method has drawbacks in that the additional logic is likely to distort the reference frequency clock output by the GPS reception module so as to degrade the quality of the system clock and increases whole manufacturing costs.